Somewhere past the grueling midpoint of tonight's CBS movie "Samaritan: The Mitch Snyder Story," Roxanne Hart, as Snyder's girlfriend, says to him, "There's a Capra festival playing downtown" and suggests the two of them go to see it.

Aside from the fact that a Capra festival would not be playing "downtown" in Washington, many a viewer will wish that the pair would go to it, and that we could join them. Anything to wrest free of "Samaritan." Events in the life of Snyder, Washington's feisty and tenacious crusader for homeless and hungry people, have been very drearily dramatized for this 2 1/2-hour production, which airs at 8:30 on Channel 9, and Martin Sheen in the title role is the original Wee Willie Washout.

The writer, Clifford Campion, and the director, Richard T. Heffron, may have felt they had a latter-day Capra hero on their hands -- and maybe they do -- but they certainly don't deploy the facts of his life with anything approaching imagination. Worse, they appear so overcome with Hollywood-liberal reverence for this chic new cause that the film fails to convey the kind of heartfelt passion and abrasive showmanship that Snyder brings to his mission. What the filmmakers probably thought would be high-impact stuff comes across as just droopy. "Samaritan" wears the longest puss of the TV-movie year.

As the film opens, the sunny and snappy Conchata Ferrell, cast against type as a destitute granny, is being tossed out of her condemned digs by insensitive District bureaucrats (this part of the movie is easy to believe). "Go call Mitch and tell him what's happening," she orders one of her children. That's the cue for Sheen's entrance as Snyder, and a listless kind of an entrance it is. "Samaritan" is a portrait of the activist as furtive mope.

To brighten things up a little, Cicely Tyson ambles by as the Apple Annie of this production, a cart-pushing street person named Muriel, who, as might be expected, possesses the Wisdom of the Ages. Unfortunately, from beneath her mountain of chunky makeup, Tyson proves maddeningly unintelligible in several of her scenes. You have to take sustenance from the sparkle in her eyes. In these surroundings, they do become a gratifying beacon, but the character as written seems too cute by half.

Hart has the most thankless role, that of the woman who supports Snyder in his work but is frustrated by his reticence to make that big emotional commitment to her. In the first half of the film, she sputters "Damn you!" to him and in the second half, mulling over the option of walking out on the guy, she pauses on the sidewalk to shout out, "Damn you, Mitch Snyder!" I am reminded of a member of a movie audience who, during a scene from "Singin' in the Rain," asked aloud while patrons chortled, "Did somebody get paid for writing dialogue like that?"

The heart of the film is Snyder's ongoing battle with bureaucracy, and any movie about that battle is bound to have its moments. The federal bureaucracy proves as unwieldy as the District's (well, almost), and a woman official ends a meeting with Snyder by saying haughtily, "Now if you'll excuse me, I have a luncheon."

The film can, and will, be defended on the grounds that it brings the problem of homelessness and poverty to the prime-time attention of the nation, which it does, certainly with more verisimilitude than Lucille Ball's romp as a bag lady earlier this season in another CBS film. And those who didn't see the Paul and Holly Fine piece about Snyder on "60 Minutes" (a fertile source of ideas for TV-movie producers) will learn a few things about a remarkable, if occasionally infuriating, human being.

But as portrayed here, Snyder's campaign lacks impact and Snyder lacks spirit. We see him sleep in the park where a D.C. rat resides, and watch as an ungrateful bum pushes a potato in his face, and listen for several minutes when, late in the film and suddenly a firebrand, Snyder lectures a congressional committee. Then comes a long fast, which you'd think would slow the film down, except that even after two hours or so, there really is nothing to slow.

TV movies often end up trivializing that which they aspire to celebrate. Snyder's plea, for "a place where people can live like people," is certainly worth reiterating. But to make that plea boring is to do it a distinct disservice.

In the course of the film, a miracle of sorts is wrought. It is the dead of winter in Washington, D.C., we have repeatedly been told, but in one exterior shot we can hear a strangely familiar sound -- yes, amazingly enough, it's a chirping cricket! In December! Now there's a bug with stamina -- but not as much as one needs to get through "Samaritan: The Mitch Snyder Story."